In communication networks, there is always a challenge to obtain good performance and capacity for a given communications protocol, its parameters and the physical environment in which the communication network is deployed.
Further, the area of communications has evolved rapidly over the last years; from traditional person-to-person phone calls to many and more advanced services; such as multimedia sessions involving e.g., multiparty video conferencing. Such services put extensive requirements on the communications network and when multimedia such as audio and video are transmitted from one device to another over the communications network, it is not uncommon that the capacity of the communications network is lower than what is required by the multimedia session to give the end-user a desired user experience. One non-limiting example is video telephony over a 3G network where on the one hand, High Definition (HD) video transmission with a bit rate of several Mbit/s could be needed to deliver a high quality end-user experience, whilst on the other hand, such a high bit rate could by the communications network only be supported under benign conditions.
As a result of varying network performance, running a multimedia session service with a high fixed bit rate over wireless communications networks (or other communications networks with time-varying throughput characteristics) may lead to quality problems and unsatisfied end-users. To mitigate this some existing services have implemented mechanisms to cope with temporarily congested networks by means of rate adaptation. Through various techniques the multimedia stream is adapted with the goal to suit present conditions of the communications channel.
In general terms, it is common that the end-user equipment and/or the network nodes of the communications network measures the perceived end-user quality or other Quality of Service (QoS) parameters such as media delay, delay jitter and packet loss that may have a correlation with the perceived end-user quality. These measurements may then be used to control the multimedia bit rate, and thus the bandwidth consumption, used by the electronic device for transmitting the multimedia stream.
However, the above outlined procedure for controlling the multimedia bit rate may not be able adapt the bit rate fast enough when considering fast time-varying channel conditions of the communications channel which may have an impact on the transmission of the multimedia. Hence, there is still a need for improved control of bandwidth consumption and/or end-user quality usable during a multimedia communications session, such as a video conferencing service.